The game saves your progress automatically every 10 minutes, as well as each time you exit the game normally; however, if there is a crash like you described, the game is not able to save the game state. In those cases, you will lose up to the last 10 minutes of play, and anything that happened during that time will be lost (including, in this case, your villager dying and being buried). That can be unsettling the first time you experience it, but it's normal after a crash.
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Barbara
Unicorn
Last Day of Work